woot.com is a popular website that uses "One Day, One Deal" as it's slogan. They feature one item per day, usually at a very good price. You buy direct from them, pay with credit card or PayPal, and usually receive the item with a week.

In their own words:
What is Woot and who's behind it?
Woot.com is an online store and community that focuses on selling cool stuff cheap. It started as an employee-store slash market-testing type of place for an electronics distributor, but it's taken on a life of its own. We anticipate profitability by 2043 – by then we should be retired; someone smarter might take over and jack up the prices. Until then, we're still the lovable scamps we've always been.